ST. PETERSBURG -- Right-hander Josh Johnson is expected to be out until at least the start of June because of soreness in his right triceps muscle.

Johnson hasn't pitched since April 21 but played catch on Wednesday and will now begin the process of working his arm back into shape. It's going to be a gradual process, though, and one that likely will take at least a few weeks.

"He's started playing catch, feeling better," general manager Alex Anthopoulos said. "We're hopeful to get him into a rehab game starting on the 21st. That's not set in stone, but that's kind of the date that we've had."

The timing of Johnson's potential return appears later than originally anticipated. Toronto's No. 4 starter would have been eligible to come off the 15-day disabled list on May 13, and there was some hope that he would be able to return to the big leagues on May 21 when the club needs another starter.

That has now been ruled out, and the Blue Jays will need to search for an alternative either through a trade or in the Minor Leagues. Toronto doesn't need a fifth starter until May 21 because of a pair of off-days next week.

Johnson is 0-1 with a 6.86 ERA in four starts this season. He is eligible for free agency at the end of the year.